I happen to have several UHF GP300's sitting around. I thought I might be able to turn one into a scanner and want to access discriminator out.
I then began searching for, and finally found, a schematic for the GP300. While searching the schematic, I found what I believed to be adequate discriminator audio output. In the linked pdf, (
https://michaelhq54.tonidoid.com/urlzdb35x) one can see PI, pin 7 (and 6 for some reason) appear to have disc. audio out. I soldered an audio cable to pads 7 and 8 (8 is ground) I connected it to my sound card line in. I scoped it with a computer oscope application, and the signal appears correct, but truthfully, I have really no idea what I am doing with the oscope.
I was able to listen to the audio out through my computer, and can tell when it receives a p25 signal (in addition to the flashing red receive light on the radio) because the amplitude of signal lessens when receiving a digital signal.
I am thinking I might need a variable resister, or perhaps an RC circuit, or perhaps, I just don't have discriminator audio. Then again, it might be something else.
Can anyone advise?
